全文获取类型
收费全文 | 2220篇 |
免费 | 112篇 |
国内免费 | 4篇 |
出版年
2023年 | 17篇 |
2022年 | 57篇 |
2021年 | 98篇 |
2020年 | 58篇 |
2019年 | 79篇 |
2018年 | 79篇 |
2017年 | 83篇 |
2016年 | 119篇 |
2015年 | 154篇 |
2014年 | 156篇 |
2013年 | 213篇 |
2012年 | 203篇 |
2011年 | 183篇 |
2010年 | 104篇 |
2009年 | 86篇 |
2008年 | 67篇 |
2007年 | 78篇 |
2006年 | 69篇 |
2005年 | 66篇 |
2004年 | 55篇 |
2003年 | 23篇 |
2002年 | 40篇 |
2001年 | 9篇 |
2000年 | 12篇 |
1999年 | 20篇 |
1998年 | 10篇 |
1997年 | 12篇 |
1996年 | 14篇 |
1995年 | 6篇 |
1994年 | 7篇 |
1993年 | 8篇 |
1992年 | 9篇 |
1991年 | 5篇 |
1990年 | 7篇 |
1989年 | 8篇 |
1988年 | 6篇 |
1987年 | 10篇 |
1986年 | 7篇 |
1985年 | 18篇 |
1984年 | 6篇 |
1982年 | 7篇 |
1981年 | 4篇 |
1979年 | 8篇 |
1978年 | 6篇 |
1976年 | 9篇 |
1975年 | 3篇 |
1974年 | 6篇 |
1973年 | 8篇 |
1970年 | 3篇 |
1966年 | 3篇 |
排序方式: 共有2336条查询结果,搜索用时 15 毫秒
91.
Paresh Vamanrao Dave Amar Niranjan Shah Pankaj B. Nimavat Bhavesh B. Modi Kirit R. Pujara Pradip Patel Keshabhai Mehariya Kiran Vaman Rade Soma Shekar Kuldeep S. Sachdeva John E. Oeltmann Ajay M. V. Kumar 《PloS one》2016,11(2)
Background
The World Health Organization recommends direct observation of treatment (DOT) to support patients with tuberculosis (TB) and to ensure treatment completion. As per national programme guidelines in India, a DOT provider can be anyone who is acceptable and accessible to the patient and accountable to the health system, except a family member. This poses challenges among children with TB who may be more comfortable receiving medicines from their parents or family members than from unfamiliar DOT providers. We conducted a non-inferiority trial to assess the effect of family DOT on treatment success rates among children with newly diagnosed TB registered for treatment during June–September 2012.Methods
We randomly assigned all districts (n = 30) in Gujarat to the intervention (n = 15) or usual-practice group (n = 15). Adult family members in the intervention districts were given the choice to become their child’s DOT provider. DOT was provided by a non-family member in the usual-practice districts. Using routinely collected clinic-based TB treatment cards, we compared treatment success rates (cured and treatment completed) between the two groups and the non-inferiority limit was kept at 5%.Results
Of 624 children with newly diagnosed TB, 359 (58%) were from intervention districts and 265 (42%) were from usual-practice districts. The two groups were similar with respect to baseline characteristics including age, sex, type of TB, and initial body weight. The treatment success rates were 344 (95.8%) and 247 (93.2%) (p = 0.11) among the intervention and usual-practice groups respectively.Conclusion
DOT provided by a family member is not inferior to DOT provided by a non-family member among new TB cases in children and can attain international targets for treatment success.Trial Registration
Clinical Trials Registry–India, National Institute of Medical Statistics (Indian Council of Medical Research) CTRI/2015/09/006229 相似文献92.
93.
Capsule: Urban Black Sparrowhawk males hunt mostly within 2.27?km of their nest during the breeding season (‘home range’ of 16.15?km2) and increased the distance slightly to 2.43?km outside of the breeding season (18.56?km2). We found high individual variation within and between six global positioning systems tagged breeding males, but no significant seasonal differences in the urban environment of Cape Town, South Africa. 相似文献
94.
Repeat monitoring is vital to measure biodiversity change. However, monitoring protocols may change, as survey techniques improve or different questions are asked. Such modifications may cause difficulties when examining changes in wildlife populations. The Southern African Bird Atlas Project (SABAP) 1 and 2 are repeat national bird surveys undertaken 20 years apart. These surveys therefore offer unrivalled potential to examine bird population changes in an African context. However, changes in protocols, both spatially and temporally, between the two surveys have raised concerns over using these data to infer population changes. In this study we use independ- ent nest survey data to test whether changes in reporting rates of Martial Eagles in the Kalahari Gemsbok National Park between the two SABAP surveys were reflected in real change in numbers of nesting pairs. From 11 quarter degree squares (QDS), covering c. 8 000 km2, both SABAP and nest surveys suggested a near identical 44% decline. Levels of agreement were weaker at the individual QDS scale, although in 67% of cases the direction of change was the same using both surveys. These results suggest that comparisons in the reporting rates between SABAP 1 and SABAP 2 accurately reflect changes in the breeding population size of this species. 相似文献
95.
Length–weight relationships of seven fish species from the upper Pelus River,Kuala Kangsar district,Perak, Malaysia
下载免费PDF全文
![点击此处可从《Zeitschrift fur angewandte Ichthyologie》网站下载免费的PDF全文](/ch/ext_images/free.gif)
M. E. M. Ikhwanuddin M. N. A. Amal S. Shohaimi A. Azizul S. Johari T. Abdullah N. R. Jamil 《Zeitschrift fur angewandte Ichthyologie》2016,32(3):511-512
Length–weight relationships (LWR) are reported for seven fish species from the upper Pelus River, Kuala Kangsar district, Perak, Malaysia. This river is located in a remote area and supplies fishes for the aboriginal peoples. Fish samplings were conducted in three different seasons, the dry (June 2014), wet (August 2014), and moderately wet (April 2015). All samples were collected using fish electro–shocker and scoop nets with a 1 cm mesh size. A total of seven LWRs were unknown to FishBase, and four new maximum fish lengths were identified in the study. 相似文献
96.
Differential foraging success across a light level spectrum explains the maintenance and spatial structure of colour morphs in a polymorphic bird
下载免费PDF全文
![点击此处可从《Ecology letters》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Detectability of different colour morphs under varying light conditions has been proposed as an important driver in the maintenance of colour polymorphism via disruptive selection. To date, no studies have tested whether different morphs have selective advantages under differing light conditions. We tested this hypothesis in the black sparrowhawk, a polymorphic raptor exhibiting a discrete white and dark morph, and found that prey provisioning rates differ between the morphs depending on light condition. Dark morphs delivered more prey in lower light conditions, while white morphs provided more prey in brighter conditions. We found support for the role of breeding season light level in explaining the clinal pattern of variation in morph ratio across the species range throughout South Africa. Our results provide the first empirical evidence supporting the hypothesis that polymorphism in a species, and the spatial structuring of morphs across its distribution, may be driven by differential selective advantage via improved crypsis, under varying light conditions. 相似文献
97.
Fluorescent bovine serum albumin interacting with the antitussive quencher dextromethorphan: a spectroscopic insight
下载免费PDF全文
![点击此处可从《Luminescence》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Amar K. Durgannavar Manjanath B. Patgar Sharanappa T. Nandibewoor Shivamurti A. Chimatadar 《Luminescence》2016,31(3):843-850
The interaction of dextromethorphan hydrobromide (DXM) with bovine serum albumin (BSA) is studied by using fluorescence spectra, UV–vis absorption, synchronous fluorescence spectra (SFS), 3D fluorescence spectra, Fourier transform infrared (FTIR) spectroscopy and circular dichroism under simulated physiological conditions. DXM effectively quenched the intrinsic fluorescence of BSA. Values of the binding constant, KA, are 7.159 × 103, 9.398 × 103 and 16.101 × 103 L/mol; the number of binding sites, n, and the corresponding thermodynamic parameters ΔG°, ΔH° and ΔS° between DXM and BSA were calculated at different temperatures. The interaction between DXM and BSA occurs through dynamic quenching and the effect of DXM on the conformation of BSA was analyzed using SFS. The average binding distance, r, between the donor (BSA) and acceptor (DXM) was determined based on Förster's theory. The results of fluorescence spectra, UV–vis absorption spectra and SFS show that the secondary structure of the protein has been changed in the presence of DXM. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
98.
Jamil?Ahmed?SoomroEmail author Zeeshan?Noor?Shaikh Tennegedara?Buhary?Saheer Suhail?Ahmed?Bijarani 《International breastfeeding journal》2016,11(1):24
Background
Breastfeeding is considered to be an important measure to achieve optimum health outcomes for children, women’s return to work has frequently been found to be a main contributor to the early discontinuation of breastfeeding. The aim of the study is to assess workplace breastfeeding support provided to working mothers in Pakistan.Method
A workplace based cross-sectional survey was conducted from April through December 2014. Employers from a representative sample of 297 workplaces were interviewed on pre-tested and structured questionnaire. The response rate was 93.7 %. Prevalence of workplace breastfeeding facilities were assessed in the light of World Alliance for Breastfeeding Action (WABA) guidelines.Results
Among non-physical facilities, all workplaces offered 3 months paid maternity leave, 45 % of the sites were offering task adjustment to mothers during lactation period. Only 15 % of the sites were offering breastfeeding breaks to working mothers. Physical facilities that include a breastfeeding corner, refrigerator for storing breast milk, breast milk pump and nursery for childcare were provided in less than 7 % of the sites. Multinational organizations provided better support compared to national organizations.Conclusion
Support for continuation of breastfeeding by working women at workplaces is inadequate; hence, women discontinue breastfeeding earlier than planned. Policies need to be developed and enforced, employers and employees need to be educated and supportive environment needs to be created to encourage and facilitate breastfeeding friendly worksite environment.99.
Mohd Ishtikhar Anam Khan Chih-Kai Chang Lilian Tsai-Wei Lin Steven S.-S. Wang 《Journal of biomolecular structure & dynamics》2016,34(7):1409-1420
6-thioguanine (6-TG) is an antineoplastic, nucleobase guanine, purine analog drug belongs to thiopurine drug-family of antimetabolites. In the present study, we report an experimental approach towards interaction mechanism of 6-TG with human serum albumin (HSA) and examine the chemical stability of HSA in the presence of denaturants such as guanidine hydrochloride (GdnHCl) and urea. Interaction of 6-TG with HSA has been studied by various spectroscopic and spectropolarimeteric methods to investigate what short of binding occurs at physiological conditions. 6-TG binds in the hydrophobic cavity of subdomain IIA of HSA by static quenching mechanism which induces conformation alteration in the protein structure. That helpful for further study of denaturation process where change in secondary structures causes unfolding of protein that also responsible for severance of domain III from rest of the protein part. We have also performed molecular simulation and molecular docking study in the presence of denaturating agents to determine the binding property of 6-TG and the effect of denaturating agents on the structural activity of HSA. We had found that GdnHCl is more effective denaturating agent when compared to urea. Hence, this study provides straight evidence of the binding mechanism of 6-TG with HSA and the formation of intermediate or unfolding transition that causes unfolding of HSA. 相似文献